With modem hearing aid devices there are a large number of possible options for adjusting the transmission function, in other words the gain of an input signal over frequency. In particular the transmission function of a modem hearing aid device can be adjusted by tailoring the hearing aid device to the individual hearing loss of a user.
A method for tailoring the transmission characteristics of a hearing aid device defined by parameters specific to the hearing aid device using a personal computer is known from DE 44 18 203 C2, a memory for base values of a hearing aid device setting in conjunction with an algorithm and a data memory supplying a transmission characteristic of the hearing aid device and displaying it on the screen of the personal computer as a graphic curve.
It is also known that the transmission response of a hearing aid device can also change during normal operation of the hearing aid device. On the one hand the user can change the transmission characteristics of the hearing aid device by manual activation of operating elements on the hearing aid or a remote control unit. It is thus possible for example to switch between different hearing programs or to vary the volume setting. Modem hearing aid devices are also frequently equipped with different automatic systems, which automatically influence the transmission function as a function of the current ambient situation or specific system states.
A method for operating a hearing aid device is known from DE 101 31 964 A1, in which a transmission characteristic of maximum gain over frequency is determined. If, due to an automatic or manual change of parameters relating to signal processing in the hearing aid device, the gain is now increased beyond the characteristic of maximum gain in one specific frequency range at least, the resulting gain in this frequency range is limited automatically to the preset maximum gain for the frequency range in question.
Hearing aid device wearers frequently encounter the problem that the speech intelligibility they experience does not correspond to the speech intelligibility of a person with normal hearing, despite the use of a hearing aid device. Different speech intelligibility models are known from the prior art, which show the frequency ranges that are particularly important for speech intelligibility. This knowledge can advantageously also be used to adjust devices that reproduce or transmit speech, such as hearing aid devices.
A method is known from U.S. Pat. No. 5,729,658, with which speech intelligibility can be quantified for a device that transmits, amplifies or reproduces acoustic speech signals. This makes it possible to compare different devices or different settings of a device in respect of their speech reproduction.